[pure-silver] Re: Problems with KRST????

From: Bogdan Karasek <bkarasek@xxxxxxxxxxxx>

To: pure-silver@xxxxxxxxxxxxx

Date: Sat, 05 Apr 2008 08:59:25 -0400

Hello Richard,

Thanks for the information on KBT. I'll look into it once I figure out
what's contaminating my KRST toning. Will try different papers,
different tray and see what happens. All this is very very strange.

Had to drop out of the discussion last night due to different time zone
on the east coast. Marshall McLuhan was partially right about the
global village ..... people communicating from different time zones,
different parts of the world.

I'll try the different paper route, Ilford Fiber and Agfa MultiClassic
but I find it strange that the previous poster has been using Kentmere
with no ill effect, except that I don't know what KBT stands for ;)

Cheers,
Bogdan

KBT = Kodak Brown Toner. KBT is a polysulfide toner similar to Kodak T-8 and to
"new" Viradon. It is a concentrated solution of Liver of Sulphur. KBT has the
advantage that it tones all densities uniformly (no split toning) so it useful for image
protection where minimum change in color or density is desired. A version of this type of
toner is currently recommended by the Image Permanence Institute for use on microfilm
instead of diluted KRST. IPI published its own formula to avoid the problem encountered
with KRST which evidently changed somehow during its manufacturing lifetime. However KBT
works fine for this. KBT is a direct toner like KRST, that is the print or film is
immersed in it with no previous bleaching step. It is recommended that a 10% solution of
sodium sulfite be used immediately following toning to stop the toning process and to
clear any yellow stain. I've found that normal working solution of Kodak wash aid works
fine even though its only about 2% su

lfite. Polysulfide toners have the peculiar property of toning faster as they become exhausted or more diluted so, unless the sulfite bath is used, the toned prints or film will continue toning in the wash bath until a substantial amount of the toner is removed. If not washed out quickly enough the toner can leave a peach colored stain. I have not found this to be a problem in practice. Like any toner KBT will work better for some papers than for others. Like KRST it will protect the image of any paper or film even when it makes little difference in image color but if one desires a color change the performance must be determined by experiment.

As a general rule (but with exceptions) toners are more effective on warm tone paper than cold. This is partly due to the grain size but can be affected by other things such as the balance of chloride and bromide in the paper. Toners are also affected by the developer so one must try the combination to find out how it looks.

--
Richard Knoppow
dickburk@xxxxxxxxxxxxx
Los Angeles, CA, USA
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--
________________________________________________________________
Bogdan Karasek
Montréal, Québec bogdan@xxxxxxxxxxxxxxx
Canada www.bogdanphoto.com
"I bear witness"
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